Are Targeted Drugs the Future in Colorectal Cancer?

This transcript has been edited for clarity. 

Hello. I'm David Kerr, professor of cancer medicine at the University of Oxford. Welcome back, everybody, from the European Society for Medical Oncology (ESMO) Congress in the wonderful city of Barcelona. I was coming from ESMO drenched in huge amounts of new data. 

One of the things I picked up on was a nice mini-symposium on gastrointestinal cancer led by Sara Lonardi, who made an excellent presentation, picking out three abstracts. They looked at molecularly targeted drugs, some early-stage and a later-stage study in which there's some evidence of promise.

She talked a little about the preliminary results from three trials suggesting some benefits, pretty marginal, of cetuximab plus irinotecan in patients who'd already had epidermal growth factor receptor (EGFR) receptor inhibitory treatment. 

Amivantamab plus FOLFOX or FOLFIRI was also discussed. This is a bispecific antibody against EGFR and MET. Again, very early, but there are some potential marginal benefits coming through. She also discussed the results of a larger phase 3 randomized trial with an old friend, ramucirumab, the anti-angiogenic agent, in which the ramucirumab in combination with trifluridine-tipiracil failed to meet its primary endpoint of improving overall survival.

There were some interesting post hoc subgroup analyses showing potential benefits for women, left-sided tumors, and so on. She made an excellent presentation, which she summarized by saying that the future of colorectal cancer treatment lies in further defining molecularly targeted treatment.

Nobody would disagree with that. What is interesting, though, is that, if I were to use the analogy of mining, the more deeply we mine, perhaps the lower marginal the benefits are becoming. There's no doubt that we're understanding better the exquisite machinery of cell signaling. We understand that there's redundancy, there's repeatability, and the possibility of emergence of resistance can come quite quickly. 

Although we can develop ever more precise molecularly targeted drugs, it does seem as if the clinical benefits of these, in some cases, are marginally small. I'd like to suggest that, in addition to Sara's call for more molecularly targeted drugs, we should think about cellular targets. 

We did a large amount of work (as have many others, of course) looking at the immune tumor microenvironment and trying to, in a way, separate and understand the contribution of the individual component cells — of which there are many, including cancer-associated fibroblasts, natural killer (NK) cells, whole hosts of different types of T-cell subsets, B cells, tumor-associated neutrophils, and so on — and how these interact together and of interact with the epithelial colorectal cancer cells. 

We are collaborating with Patrick Soon-Shiong, a clever chap, who believes in combination immunotherapy, dissecting and understanding the individual role of these different cells, and coming up with cellular therapies or targeted therapies that either inhibit or stimulate some of the different cell components to be the way ahead for an immunologically cold tumor such as microsatellite-stable colorectal cancer.

For example, we're looking at combinations of our histone deacetylase (HDAC) inhibitor, which switches on the machinery of antigen presentation, upregulating major histocompatibility complex (MHC) class 1 and class 2, and some other of the molecules involved in antigen chopping and presentation; it's like turning a microsatellite-stable immunologically cold tumor hot; an interleukin-15 superagonist that stimulates NK cells; and we've found a way to manipulate and reduce the number of Treg cells. 

We have various approaches to reducing the microenvironment transforming growth factor beta and some of the downstream elements from that. We can look at combinatorial immunotherapy, but thinking at a cellular level and developing anticancer agents that either activate or inhibit these different cell components. I'd bring the two together. 

Of course, the future has got to be better molecularly targeted drugs, but let's think at a macro level as to how we can look at the different cellular interactions within the tumor microenvironment, and perhaps through that, come up with synergistic immunotherapeutic combinations.

Thanks for listening. For the time being, Medscapers, over and out.